Wikipedia

TSR, Inc. was an American game publishing company and the publisher of Dungeons & Dragons (D&D).

When Gary Gygax could not find a publisher for D&D, a new type of game he and Dave Arneson were co-developing, Gygax and Don Kaye founded Tactical Studies Rules in October, 1973, to self-publish their products. However, needing immediate financing to bring their new game to market before several similar competing products were released, Gygax and Kaye brought in Brian Blume in December as an equal partner. When Kaye unexpectedly died in 1975, the Tactical Studies Rules partnership restructured into TSR Hobbies, Inc. and accepted investment from Blume's father Melvin. With the now popular D&D as its main product, TSR Hobbies became a major force in the games industry by the late 1970s. Melvin Blume eventually transferred his shares to his other son Kevin, making the two Blume brothers the largest shareholders in TSR Hobbies.

TSR Hobbies ran into financial difficulties in the spring of 1983, prompting the company to split into four independent businesses, with game publishing and development continuing as TSR, Inc. (TSR) After losing their executive positions due to the company's underperformance, the Blume brothers subsequently sold their shares to TSR Vice President Lorraine Williams, who in turn engineered Gygax's ouster from the company in October 1985. TSR saw prosperity under Williams, but by 1995, had fallen behind their competitors in overall sales. TSR was left unable to cover its publishing costs due to a variety of factors, so facing insolvency, TSR was purchased in 1997 by Wizards of the Coast (WotC). WotC initially retained use of the TSR name for their D&D products, but by 2000, the TSR moniker had been dropped, coinciding with the release of the 3rd edition of D&D.